This invention relates to nonwoven waste barriers having adhesive properties and to absorbent articles prepared therewith. In particular, the invention relates to waste barriers for use in disposable absorbent articles such as diapers, sanitary napkins, bed pads, incontinent pads, and the like.
Conventional disposable absorbent articles generally comprise an absorbent pad positioned between a fluid permeable nonwoven topsheet and a fluid impermeable backsheet. The nonwoven topsheet draws the waste away from the contacting skin and into the absorbent batting while the fluid impermeable backsheet prevents the absorbed fluids from leaking out of the absorbent article. Numerous variations of, and elements in addition to, these basic components have been taught with each variation or additional element being directed to improving a specific characteristics of the article. Regardless of the particular construction, however, it is expected that the absorbent article will have characteristics which permit liquid to rapidly penetrate the liquid permeable topsheet while large quantities of light are absorbed by the core. Once in contact with the absorbent core, the liquid will tend to migrate or spread away from the source of discharge, thereby migrating throughout the thickness of and toward the perimeter of the absorbent core. The liquid which penetrates the thickness of the core will be prevented from wetting the vicinity surrounding the diaper by the liquid impermeable backsheet; however, the problem remains of preventing escape or leakage of liquid which migrates toward the perimeter of the absorbent article.
Providing a barrier to reduce or eliminate the amount of leakage from the perimeter of these disposable articles has become a primary concern for the manufacturers. In attempting to solve this problem the manufacturer has to consider the effects of the proposed barriers on other requirements for the article. In particular, it is essential that the barrier not reduce the absorbency of the core; it must not affect the softness or "hand" of the non-woven topsheet; no irritating compounds can be used since the uses generally contemplate contact with the skin; the barrier must be economical and, importantly, it must not reduce line speeds during production of the absorbent articles.
Prior methods to provide such barriers have been deficient in at least one of these areas. Thus, U.S. Pat. Nos. 3,520,303; 4,397,645 and Canadian No. 1,182,601 teach the insertion of a separate barrier film or other barrier construction, positioned between the topsheet and the backsheet and partially overlapping the absorbent core. Such barriers are difficult to handle in the high speed equipment and generally require two separate adhesive applications in order to affix them or require the use of heat seal equipment which may weaken the integrity of the fluid impermeable backsheet. U.S. Pat. Nos. 3,693,622 and 3,799,167 teach the use of liquid repellant compositions on either the absorbent core or nonwoven portion of the article. This approach requires the use of the fluid repellant in the form of liquid solutions which effectively saturate the surface to which they are applied. Thus, if applied to the absorbent core, the solution will substantially reduce the absorbency of the subsequent product, while if applied to the nonwoven topsheet it will completely penetrate the sheet thereby reducing the softness or feel of the nonwoven sheet which will then cause discomfort to the wearer. Furthermore, these solutions require drying or curing to effect the fluid repellency treatment, steps which substantially reduce the speeds at which the disposable articles are manufactured. For example, the U.S. Pat. No. 3,799,167 requires curing times of 15 seconds to 5 minutes; a curing time which clearly could not be tolerated in conventional diaper manufacturing equipment which produce diapers at a rate of 4 to 15 per second.